1. Field of the Invention
The present invention relates to a shift control device for controlling an automatic transmission that automatically shifts rotary power of an engine and to a method of controlling a shift control device.
2. Description of Related Art
Japanese Patent Application Publication No. 2006-336716 (JP 2006-336716 A) discloses a shift control device that includes: a basic shift control means for shifting a gear stage of a transmission of a vehicle to a gear stage in which a fuel consumption rate is the lowest within a range that the vehicle is not decelerated; and a shift inhibiting means for inhibiting an upshift by the basic shift control means for a specified time since an accelerator operation amount of the vehicle exceeds a specified amount and is then reduced.
The shift control device calculates currently required engine output, determines a hypothetical fuel consumption rate and hypothetical required torque in a case where the required engine output is maintained, and, among the gear stages in which the hypothetical required torque corresponds to the maximum torque or smaller, selects the gear stage with the lowest hypothetical fuel consumption rate as a target gear stage. In other words, the target gear stage is selected as a gear stage in which the current hypothetical fuel consumption rate is the lowest.